Date: Wed, 3 Jan 1996 11:41:33 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: bde@zeta.org.au (Bruce Evans) Cc: bde@zeta.org.au, phk@critter.tfs.com, freebsd-hackers@FreeBSD.ORG, jkh@time.cdrom.com, obrien@cs.ucdavis.edu Subject: Re: X for install Message-ID: <199601031841.LAA15134@phaeton.artisoft.com> In-Reply-To: <199601031111.WAA02552@godzilla.zeta.org.au> from "Bruce Evans" at Jan 3, 96 10:11:33 pm
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> If you disabled the drive then both probing the drive and reading it > will fail. It isn't fair to ask FreeBSD to determine the BIOS geometry > in that case. The geometry might depend on how the drive is enabled > (with or without boot manager...). Determine if it has a partition table. If it has a partition table, determine if it has DOS partitions. If it has DOS partitions, then find them on the disk. Make sure the 32 bit absolute sector address in the partition table entry is correct. It won't be for DOS fdisk versions before 3.0x, and some utilities don't set it correctly. Fix the checksum after the AA55 (why isn't this done now?). Then from protected mode *always* use the 32 bit sector offset instead of the C/H/S value. For DOS partition mounting, note that the partitions start/stop on an even cylinder boundry and use this information to determine C/H/S geometry (only works if you have the 32 bit offset and size already). Much of this is documented in the PReP standard, which requires the use of the 32 bit offset/size value for PPCBug and for OpenBoot. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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